In the study the researchers evaluated the effectiveness of tTG in a general referral practice medical setting by reviewing 137 patients who had duodenal biopsy and tTG testing for celiac disease, out of which 117 were biopsy confirmed. Serum from these individuals was sent to four different commercial laboratories for analysis, and the results from these labs were compared. The average tTG sensitivity overall was 71% with a specificity of 67%. In patients with total villous atrophy sensitivity was as high as 92%, and in those with only partial villous atrophy it was as low as 38%. One of the four laboratories tested samples from 48 of the patients and their sensitivity was only 51%, while the specificity was 100%.
According to these results it appears that tTG testing—at least outside of the clinical study setting—may not be accurate, and its accuracy depends heavily on which lab is used. Unfortunately the researchers did not reveal the names of the commercial laboratories used in their study, but we hope they will do so when the study is published.